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openssl/crypto/hpke/hpke_util.c
Stephen Farrell a1c0306895 Add additional internal HPKE hardening checks resulting from code audit. 
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22493)
2023-11-03 09:10:19 +01:00

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/*
* Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <string.h>
#include <openssl/core_names.h>
#include <openssl/kdf.h>
#include <openssl/params.h>
#include <openssl/err.h>
#include <openssl/proverr.h>
#include <openssl/hpke.h>
#include <openssl/sha.h>
#include <openssl/rand.h>
#include "crypto/ecx.h"
#include "crypto/rand.h"
#include "internal/hpke_util.h"
#include "internal/packet.h"
#include "internal/nelem.h"
#include "internal/common.h"
/*
* Delimiter used in OSSL_HPKE_str2suite
*/
#define OSSL_HPKE_STR_DELIMCHAR ','
/*
* table with identifier and synonym strings
* right now, there are 4 synonyms for each - a name, a hex string
* a hex string with a leading zero and a decimal string - more
* could be added but that seems like enough
*/
typedef struct {
uint16_t id;
char *synonyms[4];
} synonymttab_t;
/* max length of string we'll try map to a suite */
#define OSSL_HPKE_MAX_SUITESTR 38
/* Define HPKE labels from RFC9180 in hex for EBCDIC compatibility */
/* ASCII: "HPKE-v1", in hex for EBCDIC compatibility */
static const char LABEL_HPKEV1[] = "\x48\x50\x4B\x45\x2D\x76\x31";
/*
* Note that if additions are made to the set of IANA codepoints
* and the tables below, corresponding additions should also be
* made to the synonymtab tables a little further down so that
* OSSL_HPKE_str2suite() continues to function correctly.
*
* The canonical place to check for IANA registered codepoints
* is: https://www.iana.org/assignments/hpke/hpke.xhtml
*/
/*
* @brief table of KEMs
* See RFC9180 Section 7.1 "Table 2 KEM IDs"
*/
static const OSSL_HPKE_KEM_INFO hpke_kem_tab[] = {
#ifndef OPENSSL_NO_EC
{ OSSL_HPKE_KEM_ID_P256, "EC", OSSL_HPKE_KEMSTR_P256,
LN_sha256, SHA256_DIGEST_LENGTH, 65, 65, 32, 0xFF },
{ OSSL_HPKE_KEM_ID_P384, "EC", OSSL_HPKE_KEMSTR_P384,
LN_sha384, SHA384_DIGEST_LENGTH, 97, 97, 48, 0xFF },
{ OSSL_HPKE_KEM_ID_P521, "EC", OSSL_HPKE_KEMSTR_P521,
LN_sha512, SHA512_DIGEST_LENGTH, 133, 133, 66, 0x01 },
# ifndef OPENSSL_NO_ECX
{ OSSL_HPKE_KEM_ID_X25519, OSSL_HPKE_KEMSTR_X25519, NULL,
LN_sha256, SHA256_DIGEST_LENGTH,
X25519_KEYLEN, X25519_KEYLEN, X25519_KEYLEN, 0x00 },
{ OSSL_HPKE_KEM_ID_X448, OSSL_HPKE_KEMSTR_X448, NULL,
LN_sha512, SHA512_DIGEST_LENGTH,
X448_KEYLEN, X448_KEYLEN, X448_KEYLEN, 0x00 }
# endif
#else
{ OSSL_HPKE_KEM_ID_RESERVED, NULL, NULL, NULL, 0, 0, 0, 0, 0x00 }
#endif
};
/*
* @brief table of AEADs
* See RFC9180 Section 7.2 "Table 3 KDF IDs"
*/
static const OSSL_HPKE_AEAD_INFO hpke_aead_tab[] = {
{ OSSL_HPKE_AEAD_ID_AES_GCM_128, LN_aes_128_gcm, 16, 16,
OSSL_HPKE_MAX_NONCELEN },
{ OSSL_HPKE_AEAD_ID_AES_GCM_256, LN_aes_256_gcm, 16, 32,
OSSL_HPKE_MAX_NONCELEN },
#if !defined(OPENSSL_NO_CHACHA) && !defined(OPENSSL_NO_POLY1305)
{ OSSL_HPKE_AEAD_ID_CHACHA_POLY1305, LN_chacha20_poly1305, 16, 32,
OSSL_HPKE_MAX_NONCELEN },
#endif
{ OSSL_HPKE_AEAD_ID_EXPORTONLY, NULL, 0, 0, 0 }
};
/*
* @brief table of KDFs
* See RFC9180 Section 7.3 "Table 5 AEAD IDs"
*/
static const OSSL_HPKE_KDF_INFO hpke_kdf_tab[] = {
{ OSSL_HPKE_KDF_ID_HKDF_SHA256, LN_sha256, SHA256_DIGEST_LENGTH },
{ OSSL_HPKE_KDF_ID_HKDF_SHA384, LN_sha384, SHA384_DIGEST_LENGTH },
{ OSSL_HPKE_KDF_ID_HKDF_SHA512, LN_sha512, SHA512_DIGEST_LENGTH }
};
/**
* Synonym tables for KEMs, KDFs and AEADs: idea is to allow
* mapping strings to suites with a little flexibility in terms
* of allowing a name or a couple of forms of number (for
* the IANA codepoint). If new IANA codepoints are allocated
* then these tables should be updated at the same time as the
* others above.
*
* The function to use these is ossl_hpke_str2suite() further down
* this file and shouldn't need modification so long as the table
* sizes (i.e. allow exactly 4 synonyms) don't change.
*/
static const synonymttab_t kemstrtab[] = {
{OSSL_HPKE_KEM_ID_P256,
{OSSL_HPKE_KEMSTR_P256, "0x10", "0x10", "16" }},
{OSSL_HPKE_KEM_ID_P384,
{OSSL_HPKE_KEMSTR_P384, "0x11", "0x11", "17" }},
{OSSL_HPKE_KEM_ID_P521,
{OSSL_HPKE_KEMSTR_P521, "0x12", "0x12", "18" }},
# ifndef OPENSSL_NO_ECX
{OSSL_HPKE_KEM_ID_X25519,
{OSSL_HPKE_KEMSTR_X25519, "0x20", "0x20", "32" }},
{OSSL_HPKE_KEM_ID_X448,
{OSSL_HPKE_KEMSTR_X448, "0x21", "0x21", "33" }}
# endif
};
static const synonymttab_t kdfstrtab[] = {
{OSSL_HPKE_KDF_ID_HKDF_SHA256,
{OSSL_HPKE_KDFSTR_256, "0x1", "0x01", "1"}},
{OSSL_HPKE_KDF_ID_HKDF_SHA384,
{OSSL_HPKE_KDFSTR_384, "0x2", "0x02", "2"}},
{OSSL_HPKE_KDF_ID_HKDF_SHA512,
{OSSL_HPKE_KDFSTR_512, "0x3", "0x03", "3"}}
};
static const synonymttab_t aeadstrtab[] = {
{OSSL_HPKE_AEAD_ID_AES_GCM_128,
{OSSL_HPKE_AEADSTR_AES128GCM, "0x1", "0x01", "1"}},
{OSSL_HPKE_AEAD_ID_AES_GCM_256,
{OSSL_HPKE_AEADSTR_AES256GCM, "0x2", "0x02", "2"}},
{OSSL_HPKE_AEAD_ID_CHACHA_POLY1305,
{OSSL_HPKE_AEADSTR_CP, "0x3", "0x03", "3"}},
{OSSL_HPKE_AEAD_ID_EXPORTONLY,
{OSSL_HPKE_AEADSTR_EXP, "ff", "0xff", "255"}}
};
/* Return an object containing KEM constants associated with a EC curve name */
const OSSL_HPKE_KEM_INFO *ossl_HPKE_KEM_INFO_find_curve(const char *curve)
{
int i, sz = OSSL_NELEM(hpke_kem_tab);
for (i = 0; i < sz; ++i) {
const char *group = hpke_kem_tab[i].groupname;
if (group == NULL)
group = hpke_kem_tab[i].keytype;
if (OPENSSL_strcasecmp(curve, group) == 0)
return &hpke_kem_tab[i];
}
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CURVE);
return NULL;
}
const OSSL_HPKE_KEM_INFO *ossl_HPKE_KEM_INFO_find_id(uint16_t kemid)
{
int i, sz = OSSL_NELEM(hpke_kem_tab);
/*
* this check can happen if we're in a no-ec build and there are no
* KEMS available
*/
if (kemid == OSSL_HPKE_KEM_ID_RESERVED) {
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CURVE);
return NULL;
}
for (i = 0; i != sz; ++i) {
if (hpke_kem_tab[i].kem_id == kemid)
return &hpke_kem_tab[i];
}
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CURVE);
return NULL;
}
const OSSL_HPKE_KEM_INFO *ossl_HPKE_KEM_INFO_find_random(OSSL_LIB_CTX *ctx)
{
uint32_t rval = 0;
int err = 0;
size_t sz = OSSL_NELEM(hpke_kem_tab);
rval = ossl_rand_uniform_uint32(ctx, sz, &err);
return (err == 1 ? NULL : &hpke_kem_tab[rval]);
}
const OSSL_HPKE_KDF_INFO *ossl_HPKE_KDF_INFO_find_id(uint16_t kdfid)
{
int i, sz = OSSL_NELEM(hpke_kdf_tab);
for (i = 0; i != sz; ++i) {
if (hpke_kdf_tab[i].kdf_id == kdfid)
return &hpke_kdf_tab[i];
}
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KDF);
return NULL;
}
const OSSL_HPKE_KDF_INFO *ossl_HPKE_KDF_INFO_find_random(OSSL_LIB_CTX *ctx)
{
uint32_t rval = 0;
int err = 0;
size_t sz = OSSL_NELEM(hpke_kdf_tab);
rval = ossl_rand_uniform_uint32(ctx, sz, &err);
return (err == 1 ? NULL : &hpke_kdf_tab[rval]);
}
const OSSL_HPKE_AEAD_INFO *ossl_HPKE_AEAD_INFO_find_id(uint16_t aeadid)
{
int i, sz = OSSL_NELEM(hpke_aead_tab);
for (i = 0; i != sz; ++i) {
if (hpke_aead_tab[i].aead_id == aeadid)
return &hpke_aead_tab[i];
}
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_AEAD);
return NULL;
}
const OSSL_HPKE_AEAD_INFO *ossl_HPKE_AEAD_INFO_find_random(OSSL_LIB_CTX *ctx)
{
uint32_t rval = 0;
int err = 0;
/* the minus 1 below is so we don't pick the EXPORTONLY codepoint */
size_t sz = OSSL_NELEM(hpke_aead_tab) - 1;
rval = ossl_rand_uniform_uint32(ctx, sz, &err);
return (err == 1 ? NULL : &hpke_aead_tab[rval]);
}
static int kdf_derive(EVP_KDF_CTX *kctx,
unsigned char *out, size_t outlen, int mode,
const unsigned char *salt, size_t saltlen,
const unsigned char *ikm, size_t ikmlen,
const unsigned char *info, size_t infolen)
{
int ret;
OSSL_PARAM params[5], *p = params;
*p++ = OSSL_PARAM_construct_int(OSSL_KDF_PARAM_MODE, &mode);
if (salt != NULL)
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
(char *)salt, saltlen);
if (ikm != NULL)
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
(char *)ikm, ikmlen);
if (info != NULL)
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
(char *)info, infolen);
*p = OSSL_PARAM_construct_end();
ret = EVP_KDF_derive(kctx, out, outlen, params) > 0;
if (!ret)
ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_DURING_DERIVATION);
return ret;
}
int ossl_hpke_kdf_extract(EVP_KDF_CTX *kctx,
unsigned char *prk, size_t prklen,
const unsigned char *salt, size_t saltlen,
const unsigned char *ikm, size_t ikmlen)
{
return kdf_derive(kctx, prk, prklen, EVP_KDF_HKDF_MODE_EXTRACT_ONLY,
salt, saltlen, ikm, ikmlen, NULL, 0);
}
/* Common code to perform a HKDF expand */
int ossl_hpke_kdf_expand(EVP_KDF_CTX *kctx,
unsigned char *okm, size_t okmlen,
const unsigned char *prk, size_t prklen,
const unsigned char *info, size_t infolen)
{
return kdf_derive(kctx, okm, okmlen, EVP_KDF_HKDF_MODE_EXPAND_ONLY,
NULL, 0, prk, prklen, info, infolen);
}
/*
* See RFC 9180 Section 4 LabelExtract()
*/
int ossl_hpke_labeled_extract(EVP_KDF_CTX *kctx,
unsigned char *prk, size_t prklen,
const unsigned char *salt, size_t saltlen,
const char *protocol_label,
const unsigned char *suiteid, size_t suiteidlen,
const char *label,
const unsigned char *ikm, size_t ikmlen)
{
int ret = 0;
size_t label_hpkev1len = 0;
size_t protocol_labellen = 0;
size_t labellen = 0;
size_t labeled_ikmlen = 0;
unsigned char *labeled_ikm = NULL;
WPACKET pkt;
label_hpkev1len = strlen(LABEL_HPKEV1);
protocol_labellen = strlen(protocol_label);
labellen = strlen(label);
labeled_ikmlen = label_hpkev1len + protocol_labellen
+ suiteidlen + labellen + ikmlen;
labeled_ikm = OPENSSL_malloc(labeled_ikmlen);
if (labeled_ikm == NULL)
return 0;
/* labeled_ikm = concat("HPKE-v1", suiteid, label, ikm) */
if (!WPACKET_init_static_len(&pkt, labeled_ikm, labeled_ikmlen, 0)
|| !WPACKET_memcpy(&pkt, LABEL_HPKEV1, label_hpkev1len)
|| !WPACKET_memcpy(&pkt, protocol_label, protocol_labellen)
|| !WPACKET_memcpy(&pkt, suiteid, suiteidlen)
|| !WPACKET_memcpy(&pkt, label, labellen)
|| !WPACKET_memcpy(&pkt, ikm, ikmlen)
|| !WPACKET_get_total_written(&pkt, &labeled_ikmlen)
|| !WPACKET_finish(&pkt)) {
ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
goto end;
}
ret = ossl_hpke_kdf_extract(kctx, prk, prklen, salt, saltlen,
labeled_ikm, labeled_ikmlen);
end:
WPACKET_cleanup(&pkt);
OPENSSL_cleanse(labeled_ikm, labeled_ikmlen);
OPENSSL_free(labeled_ikm);
return ret;
}
/*
* See RFC 9180 Section 4 LabelExpand()
*/
int ossl_hpke_labeled_expand(EVP_KDF_CTX *kctx,
unsigned char *okm, size_t okmlen,
const unsigned char *prk, size_t prklen,
const char *protocol_label,
const unsigned char *suiteid, size_t suiteidlen,
const char *label,
const unsigned char *info, size_t infolen)
{
int ret = 0;
size_t label_hpkev1len = 0;
size_t protocol_labellen = 0;
size_t labellen = 0;
size_t labeled_infolen = 0;
unsigned char *labeled_info = NULL;
WPACKET pkt;
label_hpkev1len = strlen(LABEL_HPKEV1);
protocol_labellen = strlen(protocol_label);
labellen = strlen(label);
labeled_infolen = 2 + okmlen + prklen + label_hpkev1len
+ protocol_labellen + suiteidlen + labellen + infolen;
labeled_info = OPENSSL_malloc(labeled_infolen);
if (labeled_info == NULL)
return 0;
/* labeled_info = concat(okmlen, "HPKE-v1", suiteid, label, info) */
if (!WPACKET_init_static_len(&pkt, labeled_info, labeled_infolen, 0)
|| !WPACKET_put_bytes_u16(&pkt, okmlen)
|| !WPACKET_memcpy(&pkt, LABEL_HPKEV1, label_hpkev1len)
|| !WPACKET_memcpy(&pkt, protocol_label, protocol_labellen)
|| !WPACKET_memcpy(&pkt, suiteid, suiteidlen)
|| !WPACKET_memcpy(&pkt, label, labellen)
|| !WPACKET_memcpy(&pkt, info, infolen)
|| !WPACKET_get_total_written(&pkt, &labeled_infolen)
|| !WPACKET_finish(&pkt)) {
ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
goto end;
}
ret = ossl_hpke_kdf_expand(kctx, okm, okmlen,
prk, prklen, labeled_info, labeled_infolen);
end:
WPACKET_cleanup(&pkt);
OPENSSL_free(labeled_info);
return ret;
}
/* Common code to create a HKDF ctx */
EVP_KDF_CTX *ossl_kdf_ctx_create(const char *kdfname, const char *mdname,
OSSL_LIB_CTX *libctx, const char *propq)
{
EVP_KDF *kdf;
EVP_KDF_CTX *kctx = NULL;
kdf = EVP_KDF_fetch(libctx, kdfname, propq);
if (kdf == NULL) {
ERR_raise(ERR_LIB_CRYPTO, ERR_R_FETCH_FAILED);
return NULL;
}
kctx = EVP_KDF_CTX_new(kdf);
EVP_KDF_free(kdf);
if (kctx != NULL && mdname != NULL) {
OSSL_PARAM params[3], *p = params;
if (mdname != NULL)
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
(char *)mdname, 0);
if (propq != NULL)
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_PROPERTIES,
(char *)propq, 0);
*p = OSSL_PARAM_construct_end();
if (EVP_KDF_CTX_set_params(kctx, params) <= 0) {
EVP_KDF_CTX_free(kctx);
return NULL;
}
}
return kctx;
}
/*
* @brief look for a label into the synonym tables, and return its id
* @param st is the string value
* @param synp is the synonyms labels array
* @param arrsize is the previous array size
* @return 0 when not found, else the matching item id.
*/
static uint16_t synonyms_name2id(const char *st, const synonymttab_t *synp,
size_t arrsize)
{
size_t i, j;
for (i = 0; i < arrsize; ++i) {
for (j = 0; j < OSSL_NELEM(synp[i].synonyms); ++j) {
if (OPENSSL_strcasecmp(st, synp[i].synonyms[j]) == 0)
return synp[i].id;
}
}
return 0;
}
/*
* @brief map a string to a HPKE suite based on synonym tables
* @param str is the string value
* @param suite is the resulting suite
* @return 1 for success, otherwise failure
*/
int ossl_hpke_str2suite(const char *suitestr, OSSL_HPKE_SUITE *suite)
{
uint16_t kem = 0, kdf = 0, aead = 0;
char *st = NULL, *instrcp = NULL;
size_t inplen;
int labels = 0, result = 0;
int delim_count = 0;
if (suitestr == NULL || suitestr[0] == 0x00 || suite == NULL) {
ERR_raise(ERR_LIB_CRYPTO, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
inplen = OPENSSL_strnlen(suitestr, OSSL_HPKE_MAX_SUITESTR);
if (inplen >= OSSL_HPKE_MAX_SUITESTR) {
ERR_raise(ERR_LIB_CRYPTO, ERR_R_PASSED_INVALID_ARGUMENT);
return 0;
}
/*
* we don't want a delimiter at the end of the string;
* strtok_r/s() doesn't care about that, so we should
*/
if (suitestr[inplen - 1] == OSSL_HPKE_STR_DELIMCHAR)
return 0;
/* We want exactly two delimiters in the input string */
for (st = (char *)suitestr; *st != '\0'; st++) {
if (*st == OSSL_HPKE_STR_DELIMCHAR)
delim_count++;
}
if (delim_count != 2)
return 0;
/* Duplicate `suitestr` to allow its parsing */
instrcp = OPENSSL_memdup(suitestr, inplen + 1);
if (instrcp == NULL)
goto fail;
/* See if it contains a mix of our strings and numbers */
st = instrcp;
while (st != NULL && labels < 3) {
char *cp = strchr(st, OSSL_HPKE_STR_DELIMCHAR);
/* add a NUL like strtok would if we're not at the end */
if (cp != NULL)
*cp = '\0';
/* check if string is known or number and if so handle appropriately */
if (labels == 0
&& (kem = synonyms_name2id(st, kemstrtab,
OSSL_NELEM(kemstrtab))) == 0)
goto fail;
else if (labels == 1
&& (kdf = synonyms_name2id(st, kdfstrtab,
OSSL_NELEM(kdfstrtab))) == 0)
goto fail;
else if (labels == 2
&& (aead = synonyms_name2id(st, aeadstrtab,
OSSL_NELEM(aeadstrtab))) == 0)
goto fail;
if (cp == NULL)
st = NULL;
else
st = cp + 1;
++labels;
}
if (st != NULL || labels != 3)
goto fail;
suite->kem_id = kem;
suite->kdf_id = kdf;
suite->aead_id = aead;
result = 1;
fail:
OPENSSL_free(instrcp);
return result;
}
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